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Got sole? If the minimalist running shoe movement has prompted you to ditch your running shoes, a new study might make you reconsider the benefits of lacing up.

Researchers at the University of Colorado in Boulder analysed 12 barefoot runners on a treadmill wearing lightweight shoes or nothing but lead strips taped to their bare feet. The results surprised them: Running barefoot provided no physiological benefit in efficiency. In fact, runners used 4 percent more energy per step when running barefoot.

"Running barefoot offers no metabolic advantage over running in lightweight, cushioned shoes," the researchers conclude in the study, which appears in the current issue of Medicine & Science in Sports & Exercise.

Previous studies have indicated that running barefoot is easier because there's no added weight.

But that thinking doesn't take into account every variable, including the cushioning that shoes provide.

If you're not wearing shoes, the researchers believe, your legs absorb more of the impact of running, causing them to work harder.

"What we found was that there seem to be adaptations that occur during the running stride that can make wearing shoes metabolically less costly," says Jason Franz, who led the study, told The New York Times.

"There is some evidence that shoe design characteristics other than mass may influence metabolic cost," the authors write. "Thus, we selected this running shoe in particular because it has some cushioning but no other features such as medial posting/arch support or various other motion control elements."

There may be other benefits to barefoot running that this study didn't address. The researchers didn't analyse injury risk, for example.